you've only given me 4 numbers to work with. but:

vb Code:
  1. Dim num1 As Integer = Val(num1TextBox.Text)
  2. Dim num16 As Integer = Val(num16TextBox.Text)
  3. Dim num17 As Integer = Val(num17TextBox.Text)
  4. Dim num18 As Integer = Val(num18TextBox.Text)
  5.  
  6. Dim a As Integer = math.abs(num1 - num16)
  7. Dim b As Integer = math.abs(num1 - num17)
  8. Dim c As Integer = math.abs(num1 - num18)
  9.  
  10. dim numbers() as integer = {a, b, c}
  11. array.sort(numbers)
  12.  
  13. label1.text = numbers(0)
  14. label2.text = numbers(1)
  15. label3.text = numbers(2)

there are plenty of online resources + tuition available for beginners.
try this:

http://www.homeandlearn.co.uk/NET/vbNET.html